If you've seen all those without rules changes to support the individual settings, then you're missing out. Some will play base 5e just fine, but others like Dark Sun played base 5e rules with cleric, no psionics, no muls or half-giants, no despoiling - that's not Dark Sun. Same for Dragonlance, Eberron, Ravenloft, etc.
Going down my list:
* FR set at the time of the original boxed set, using a 2nd edition module (Haunted Halls of Eveningstar). - I am unaware of any house rules beyond a few monsters being created.
* Original Dragonlance Saga - The only house rules were three wizard subclasses which nobody used.
* Shackled City - No house rules.
* Dark Sun (original adventure path) - They used the Mystic and Wizards with spell point alternative rules for the Psionics. The monsters were reskins with added powers.
* A Middle Earth game (PCs had to have more levels in Fighter, Monk or Rogue combined than any other class - worked well)
* A1 to A4 - This one had a tome of house rules, but most of them were home created feats, home created spells, detailed rules for vision, etc... None of it was necessary.
* G1 to G3 - Same rules as A1 to A4.
* Gamma World - This used reskinning of a few classes and races. Spells became technology. This one was a rough fit, but everyone had fun.
* The Sunless Citadel Adventure Path (SC, FoF, SiD, SS, HNfS, DH, LotIF, BBS) - No changes.
* A Planescape Game - A few homemade races, a lot of spells updated from prior editions,
* Ravenloft - There was a 'Dread mechanic' using our own Jenga towers. When we did something that should have been scary, we pulled a piece. If your tower fell, you were in for trouble as something very, very bad was going to happen. Beyond that, there were just a few environmental special rules (the Mists, certain spells did not work normally, etc...) and monster tweaks to made them scarier.
All in all, it was minor stuff. The levels of house rules were no greater than I saw in most games set entirely using current edition settings.
If you have played with alternate rules for them, then you see how setting fluff/lore/feel and mechanics are intertwined, and you can't publish "books of lore, good for all editions" and assume that they actually will fit all editions.
It depends upon how you define Lore. For example, There are Wikis that do exactly what I propose out there - they're just not maintained by WotC.
If you do that, you're either lying on your product or chaining yourself for future editions.
I don't get what the lie would be, and as for it having limiting facets on future editions - Not if the editions have as much in common as AD&D, 2E, 3E and 5E. Seriously: Name one thing from AD&D to 3.5 that is not easily translated to 5E
Look, I've got boxed sets of FR lore back from AD&D 2nd and Myth Drannor and the like. They didn't translate nicely to 3.0, and same for 5e. While 3.0/3.5 to 5e isn't bad for how lore feel fits into mechanics, that's not always true between editions.
AD&D, 2E, 3E and 5E all translate - lore wise - easily. As stated, I've seen all of the above work well.
If you'd like to elaborate on something that exists in your old materials that would not translate to 5E, I'd be curious to see it.